property_set.js won't modify object if value and currentValue is undefined

[makepanic]

In newer ember versions, Ember.set(object, 'field', undefined) won't set the field key on an object, because the value is undefined.
It exits earlier here which causes no object modification.

I think this is a regression (introduced in v2.7.0-beta.1), because previously it wouldn't enter that condition, if the value was undefined.

Using a 2.7.0 ember app:

On discourse:

A possible way to fix this would to reintroduce the value !== undefined check

[rwjblue]

After reviewing this a bit, I am not certain that Ember.set should actually be changed here. Ember.set isn't about guaranteeing an objects own properties, its about setting the specified property to the given value. If that property already is set to the new value, doing nothing seems like the correct thing to me.

I welcome thoughts from others (cc @krisselden / @stefanpenner), but I don't know that this is a bug...

[stefanpenner]

Ember.set isn't about guaranteeing an objects own properties, its about setting the specified property to the given value. If that property already is set to the new value, doing nothing seems like the correct thing to me.

i would tend to agree.

[poteto]

I agree that setting a previously set value to the same value should do nothing.

its about setting the specified property to the given value.

The issue is that let x = {}; Ember.set(x, 'prop', undefined) being a no-op seems inconsistent (and likely a regression given the OP). I would expect x to be set to {prop: undefined}, which is consistent with vanilla object setters

[stefanpenner]

rwjblue we could set the property and not have it emit a change event. This should align both the ES semantics, and the change tracking semantics.

cc @krisselden

[locks]

I opened the file to try and implement stef's suggestion and got intimidated by the code. Should I pursue it, and would it need new tests to be added?